Purpose: The aim of the study was to investigate the validity and predictability of a new software calculator for quantifying astigmatism induced by surgery. Techniques and methods: Using Microsoft Office Excel 2007, a new astigmatic calculator was developed , based on the Pythagorean principle and trigonometric functions. In diopters, the astigmatic magnitude was quantified and axis direction was shown in degrees. On 30 pseudophakic eyes that underwent temporal scleral incision surgery within the bag intraocular lens implantation, a calculator was applied, investigated, and analysed. With Bausch and Lomb keratometers, pre and postoperative anterior corneal curvature was measured. Similarities and differences were compared to the existing 1.1 and 2.1 calculators, and Microsoft Excel was used to perform statistical analysis. Results: Mean astigmatic pre and postoperative magnitude of 62.67 (+ /- 2.40) and 62.83 (+ /- 2.29) diopters were calculated. The mean astigmatic pre and postoperative axes were 89.74 (+ /- 1.37) and 89.51 (+ /- 1.37) degrees respectively. The Pearson coefficient (r) was calculated to be 0.91 and 0.83; the coefficient of determination ( R2) for astigmatic magnitudes and axes was calculated to be 0.82 and 0.68 respectively. For the calculation of T values, which were 0.39 and 0.26 for the astigmatic magnitude and axis, the student chi-square test was used. A P-value of less than 0.05 (p 0.16) was considered statistically significant. Validity was evaluated by y=2.83 + 0.95x for astigmatic magnitude and y=15.28 + 0.83x equations for astigmatic axis compared with existing surgically induced astigmatism calculators 1.1 and 2.1 versions and predictability was evaluated. Conclusion: The current application of Microsoft excel calculator was valid as the values for astigmatic magnitude and axis were comparable to existing SIA calculators and can be used for astigmatic predictability. Ophthalmic surgeons with fair knowledge of Microsoft office excel 2007 software are sufficient to enter the pre- and post-operative keratometric readings of their patients for assessment of sur-operative software.
Author(s) Details
Dr. Prabhakar Srinivasapuram Krishnacharya
JSS
Medical College Hospital, Jagadguru Sri Shivarathreeshwara University,
Mysore-570004, Karnataka, India.
Dr. Anuj Kumar Singal
JSS Medical College Hospital, Jagadguru Sri Shivarathreeshwara University,
Mysore-570004, Karnataka, India.
Dr. A. Shamsiya Naaz
JSS Medical College Hospital, Jagadguru Sri Shivarathreeshwara University,
Mysore-570004, Karnataka, India.
Dr. Raghavender Reddy Arra
JSS Medical College Hospital, Jagadguru Sri Shivarathreeshwara University,
Mysore-570004, Karnataka, India.
Dr. Pooja A. Angadi
Dr. Ashwini Chandramouli
JSS Medical College Hospital, Jagadguru Sri Shivarathreeshwara University, Mysore-570004, Karnataka, India.
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